#define singleton_h(name) + (instancetype)shared##name;#if __has_feature (objc_arc)#define singleton_m(name) static id _instance; + (id)allocWithZone:(struct _NSZone *)zone {     static dispatch_once_t onceToken;     dispatch_once(&onceToken, ^{         _instance = [super allocWithZone:zone];     });     return _instance; } + (instancetype)sharedOnlyoneClass {     static dispatch_once_t onceToken;     dispatch_once(&onceToken, ^{         _instance = [[self alloc] init];     });     return _instance; }#else#define singleton_m(name) static id _instance; + (id)allocWithZone:(struct _NSZone *)zone { static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ _instance = [super allocWithZone:zone]; }); return _instance; } + (instancetype)shared##name { static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ _instance = [[self alloc] init]; }); return _instance; } - (oneway void)release {    } - (id)retain {    return _instance; } - (NSUInteger)retainCount {     return 1; } - (id)autorelease {     return _instance; } + (id)copyWithZone:(struct _NSZone *)zone {     return _instance; } + (id)mutableCopyWithZone:(struct _NSZone *)zone {     return _instance; }#endif

#import <Foundation/Foundation.h>#import "Singleton.h"@interface LWTOnlyoneClass : NSObject@property (nonatomic, copy) NSString *name;singleton_h(OnlyoneClass)@end

////  LWTOnlyoneClass.m//  多线程练习 -- 单例设计模式////  Created by apple on 14-6-24.//  Copyright (c) 2014年 lwt. All rights reserved.//#import "LWTOnlyoneClass.h"@implementation LWTOnlyoneClass- (instancetype)init{    self = [super init];    if (self) {        static dispatch_once_t onceToken;        dispatch_once(&onceToken, ^{            self.name = @"jack";        });    }    return self;}singleton_m(OnlyoneClass)@end

#import <UIKit/UIKit.h>@interface LWTViewController : UIViewController@end

////  LWTViewController.m//  多线程练习 -- 单例设计模式////  Created by apple on 14-6-24.//  Copyright (c) 2014年 lwt. All rights reserved.//#import "LWTViewController.h"#import "LWTOnlyoneClass.h"@interface LWTViewController ()@end@implementation LWTViewController- (void)viewDidLoad{    [super viewDidLoad];        LWTOnlyoneClass *onlyone1 = [[LWTOnlyoneClass alloc] init];    LWTOnlyoneClass *onlyone2 = [LWTOnlyoneClass sharedOnlyoneClass];    onlyone2.name = @"Tom";    LWTOnlyoneClass *onlyone3 = [[LWTOnlyoneClass alloc] init];    onlyone3.name = @"rose";    LWTOnlyoneClass *onlyone4 = [LWTOnlyoneClass sharedOnlyoneClass];    onlyone4.name = @"jim";    //#if __has_feature (objc_arc)//    LWTOnlyoneClass *onlyone5 = [LWTOnlyoneClass sharedOnlyoneClass];//    LWTOnlyoneClass *onlyone6 = [LWTOnlyoneClass sharedOnlyoneClass];////#else//    LWTOnlyoneClass *onlyone5 = [onlyone2 copy];//    LWTOnlyoneClass *onlyone6 = [onlyone3 mutableCopy];//#endif                NSLog(@"%p -- %p -- %p -- %p", onlyone1, onlyone2, onlyone3, onlyone4);    NSLog(@"%@ -- %@ -- %@ -- %@", onlyone1.name, onlyone2.name, onlyone3.name, onlyone4.name);}@end